Glycosyl transferases are important components of the biosynthetic system that generates and modifies glycoproteins. Inherited disorders that affect the levels or structures of the transferases can result in degenerative diseases such as Carbohydrate Deficient Glycoprotein syndrome (CDGS). In order to facilitate investigation of these pathways, rabbit GnT I and human GnT II have been expressed in a transfer vector system that secretes the hybrid enzymes from the insect cells with an attached H]H[HHOHH sequence. The signal peptide is derived from mellittin and it is expected that the signal peptidase sequence .... YIYADPM... is cleaved at its Ala-Asp linkage. The molecular weights of the expressed proteins are being checked by MALDI and ESI MS to determine whether the correct proteins have been obtained and to look for post-translational modifications.